The other night, I watched a YouTube video featuring a woman standing on her bed, holding a cat upside down by its feet, then repeatedly dropping the cat onto the mattress. Amazingly, every time the cat was released, it immediately righted itself and landed on its feet.

The woman was performing the same basic experiment that French scientist Etienne Jules Marey did back in 1890. Marey, famous for investigations in which his chronophotographic camera was able to capture up to 60 consecutive frames a second, dropped a cat and filmed it. And yes, there’s a clip on YouTube:

The purpose of both of these videos was to demonstrate the cat’s unique innate ability to reorient its body during a fall. There’s even a name for this phenomenon: the “righting reflex.” Animal experts say that the righting reflex is observable in kittens as early as three to four weeks, and is fully developed at seven weeks.

How does the righting reflex work?

First, cats have supersensitive sense organs. A vestibular apparatus in their inner ear acts as a balance and orientation compass. They always know right side up. Second, cats have a unique skeletal structure - an unusually flexible backbone and the absence of a collarbone. So when a cat falls, its senses respond with lightning speed, and it is able to reorient its body and twist its head around so it can see where it’s going to land.

Beyond their amazing aerial spins, cats also have what could be called a built-in parachute. Like many small animals, they have a low body-volume-to-weight ratio, which when falling, allows them to slow their velocity by spreading out and becoming their own parachute. It’s the same kind of maneuver that flying squirrels do in mid-air.

But as amazing as their gravity-defying abilities are, cats are not invincible.

In 1987, veterinarians at New York City’s Animal Medical Center did a study of felines that had fallen from tall buildings. 90% of them survived, though most sustained serious injuries. Of those, more than one-third needed life-saving treatment, while just under a third required no treatment. What’s remarkable is that the study found that cats that fell from heights of 7 to 32 stories were less likely to die than those that fell from 2 to 6 stories.

Why? One theory is that after a certain distance, a cat reaches maximum speed and that vestibular mechanism in its ear shuts off. As a result, the cat relaxes. As any stuntman can tell you, relaxed limbs are less likely to break than unrelaxed ones. Another is that the greater height gives the cat time to adopt its parachute pose.

For those of you who enjoy physics, the “falling cat problem,” as it’s called, has been parsed in diagrams and technical language in online dissertations such as “Gauge Theory of the Falling Cat” and the Monty Python-ish sounding “Aerial Righting Reflexes in Flightless Animals.”